The field of restorative dentistry using artificial roots in the presently-preferred form of osseointegrated cylinder-shaped dental implant fixtures has progressed to the level where attention is now being given to providing restorations on them that closely replicate natural dentition in appearance, especially where the teeth emerge from the gums. The problems of achieving a natural-looking emergence profile are addressed using a technique for fabricating implant-supported restorations directly to an implant fixture, employing custom wax patterns fashioned on abutment cylinders to achieve, for example, a custom-made porcelain-fused-to-metal restoration. This technique is described in published articles which appeared in The International Journal of Oral & Maxillofacial Implants, Vol. 3, Number 1, 1988 at pages 25-26 "Single-Tooth Implant Supported Restorations" Lewis, S. G. et al., and Number 3, 1988 at pages 183-189 "The "UCLA" Abutment", Lewis, S. et al. A similar result using a different abutment is described in U.S. Pat. No. 4,988,298, which is owned by the Assignee of the present invention. The problem is incompletely addressed in U.S. Pat. No. 5,073,111 issued to Daftary Dec. 17, 1991.
The dental restoration of a wholly or partially edentulous patient with dentition supported on dental implant fixtures is now frequently done in two stages. In the first stage the implant fixture is placed and left to integrate with the jawbone. The second stage begins with re-accessing the fixture through the gum and maintaining access with a healing cap or the like, and continues through the fabrication of restorative dentition in the laboratory using measurements and other information taken from time to time from the patient. During that time the patient may have only a healing cap in his or her mouth, or according to more recent and sophisticated procedures the patient may be fitted with temporary dentition from which additional refining measurements can be taken. However, the healing abutments and the transfer copings or pick-up copings of the prior art do not cooperate to provide room for making and installing on the implant an artificial tooth having an aesthetically-pleasing or anatomically-correct emergence profile. The gingival aspect of an implant fixture is, typically not more than about 4.1 mm in diameter, whereas the longer (mesial-distal) dimension of a natural tooth where it emerges from the gum is between about 4.5 mm and about 8.0 mm. According to present practice, healing abutments, which are cylindrical in cross-section, are chosen to approximate the mesial-distal dimension of the tooth being replaced. At the same time, the transfer or pick-up copings of the prior art are all one size, about 4.5 mm in diameter. As a result, a gap is left in the gingiva, around the coping, and impression material fills this gap when an impression is taken. The gingiva also tend to collapse into this gap, resulting in less than accurate replication of the conditions in the patient's mouth. As a further consequence of these problems it is difficult to make soft tissue models accurately. Stone models replicate these errors, and this requires technicians to shape the stone manually to comply with the conditions in the patient's mouth, or risk producing a crown with an inaccurate emergence profile or crown-to-abutment margin which are misplaced. These are severe problems, resulting from the fact that the designers of prior art components have thus far failed to recognize them. The present invention teaches new surgical and laboratory components, and new procedures, which eliminate such inaccurate and time-wasting procedures, and improve the art of making anatomically-correct and aesthetically-pleasing dental restorations.